Does Arctic Sea Ice Melt Lead to More Midlatitude Cold Extremes?

Researchers cannot confirm that sea ice loss is related to colder weather in the Northern Hemisphere.

Science

A research team, including a scientist at the U.S. Department of Energy’s Pacific Northwest National Laboratory, began an effort to resolve a controversy over whether Arctic sea ice loss leads to more midlatitude weather extremes. Scientists found that previous claims of more intense extremes because of Arctic melt do not have a solid footing. One cannot rule out that a recent trend of more frequent cold weather over the Northern Hemisphere took place mostly by chance.

Impact

The research provides a new look at the possible Earth systems impact of Arctic sea ice melt. More comprehensive, inter-model-comparison-type investigations of this issue are needed.

Summary

Researchers set out to solve whether increased warming and sea ice loss in the Arctic could lead to wavier weather patterns (meaning longer and more severe heat waves or cold spells) and more extreme cold temperatures over midlatitude continents. Scientists used a wave activity metric to measure atmospheric midlatitude waviness in atmospheric model experiments perturbed using the best knowledge of surface boundary conditions. They could not detect a continent-wide increase in weather waviness. However, researchers found that sea ice loss near the Barents and Kara seas produced an anticyclonic circulation anomaly (wind moving clockwise) over north-central Eurasia. Sea ice loss increased under a future climate warming scenario and magnified the anticyclonic circulation feature, leading to more extreme cold weather over the affected area. Researchers developed wave activity diagnostics and traced the anticyclonic circulation trend back to its possible source—the Barents and Kara seas. A stronger teleconnection (effect of a climate anomaly felt elsewhere) to the wave activity in north-central Eurasia appeared to be from La Niña-like sea surface temperatures in the Pacific.